The manufacture of strands from attenuable, thermoplastic materials, for example, glass, by pulling streams of the attenuable material from the orifices of the bushing is, of course, a known process. In this process, the streams of attenuable material harden and solidify into filaments as they are drawn away from the orifices in the bushing. A strand composed of a number of these filaments is wound on a sleeve mounted on a rotating collet. This winding subjects the strand, including the streams of material drawn from the orifices, to a pull or tension that draws out, i.e. attenuates, the portions of the filaments that are not yet hardened or solidified.
In such winding operations, it is necessary from time to time to restart the winding operation, after an interruption, by winding the strand on a new sleeve. The strand wound on each sleeve must be subjected to an unvarying attenuation process throughout the length of the winding so that the diameter of the strand is held as constant as possible. This is accomplished principally by winding the strand at a constant speed. With non-automatic winders (winders having only a single collet that must be stopped when the winding is at capacity, the finished winding manually removed, and a new winding started on the same collet), such restarts are necessary each time a full winding is removed and each time there is a strand rupture. With automatic winders (winders having two or more collets mounted on a turret and mechanism for automatically commencing winding on an empty collet after the winding on a preceding collet has reached capacity) such restarts are necessary after strand ruptures.
However, it should be realized that when the strand prematurely ruptures or when the strand pulling operation is interrupted by the necessity of removing a winding that is at capacity, the pulling operation is slowed or stopped. When the strand is drawn slowly, the streams of attenuable material form relatively large diameter filaments. It is undesirable to have strand formed of these relatively large diameter filaments in a winding, as the winding would be unacceptable to users of the product because of the variations in the diameter.
Prior to this, with non-automatic winders, following the completion of each winding and each time the strand ruptured prematurely during winding, the restarting operation involved the use of two men, one above the winder to pull the filaments from the bushing to restart the filament formation at the bushing and a second man at the level of the winder who, in either case, removed the winding on the collet and restarted a new winding on the collet. In the case of automatic winders it was also necessary to employ two men to restart the winding operation in the event of strand rupture. The restarting operation in the event of strand rupture with automatic winders is essentially the same as that explained previously with respect to non-automatic winders. These prior restarting procedures have several disadvantages. They required the use of two men and the attendant high labor costs. Also, because the labor force in the winding operation was split into two groups, those at the level of the bushings and those at the level of the winders, it was often the case that, while two men were attending to a rupture, or in the case of non-automatic winders, the removal of the finished winding from a collet, that other ruptures or completion of windings at other winders would occur. These could not be attended to until the two men had completed a restart of the first interrupted operation and this resulted in losing winder utilization time and also resulted in the loss of significant amounts of glass.
The invention described and claimed herein provides for the restarting of the winding operation by a man at the level of the bushings. It is possible to reduce the number of men at the level of the winders, as it is only necessary for them to remove full or practically completed strand windings and it is not necessary for them to take the time to work with the man at the bushing level to restart the winding. This allows the man at the bushing level to effect the restart or the reset of the winding more quickly and significantly reduces winder down time and the amount of glass lost during strand ruptures.
In our prior co-pending application, a method and apparatus are described for affixing a continuous strand, notably glass strand, on a collet designed to attenuate the glass and form a winding of the resulting strand. In that application, the collet comprises, at one end, a starting drum on which the strand is affixed as the collet begins rotation. This process is characterized by bringing the strand into contact with the front face of the drum, and then catching it by engaging means that are disposed on the periphery of the drum. The engaging means conduct the strand into a circular groove provided on the drum in a way to wind the thread in this groove until the collet is brought to normal winding speed.
In the arrangements disclosed in our prior application, the thread is applied along a diameter of the front face of the drum, and is caught by two strand-engaging elements disposed along a diameter of this front face. The strand-engaging elements in these prior arrangements comprise slots parallel to the axis of the collet and disposed between the front face of the drum and the groove, to conduct the thread into the groove.
These prior arrangements proved to be satisfactory; however, proper functioning was influenced by alignment of the strand along a diameter of the collet and by the accumulation of size on the front face of the starting drum. Misalignment of the strand or the accumulation of size could cause the strand to be engaged by only one of the strand-engaging slots and this can result in a failure of the strand to wind on the collet.